Abstract

We consider a Hamiltonian with cutoffs describing the weak decay
of spin 1 massive bosons into the full family of leptons. The Hamiltonian is
a self-adjoint operator in an appropriate Fock space with a unique ground
state. We prove a Mourre estimate and a limiting absorption principle above
the ground state energy and below the first threshold for a sufficiently small
coupling constant. As a corollary, we prove the absence of eigenvalues and absolute
continuity of the energy spectrum in the same spectral interval.